Apparatus for forming and advancing transverse yarn reaches

ABSTRACT

A method is described for making a fiber-reinforced composite film sheet (fiber/film laminate) by continuously forming a first planar lap from a plurality of machine-direction (MD) fibers, continuously forming a second planar lap from a single fiber as transverse-direction (TD) reaches which are connected by 180° loops by stretching the fiber between a horizontally diverging pair of chain assemblies, continuously straddling both laps with a pair of co-extruded films which extend sidewardly beyond the loops, vertically converging the films and fibers to form a sandwich, edge sealing the sandwich within strips close to its side edges but inwardly of the loops, lifting the loops from the chain assemblies, sidewardly smoothing and tautening the sandwich, and laminating the sandwich with heat and pressure to form the composite film sheet and application for carrying out this method.

This is a division of copending application SER. NO. 307,417,filed Oct.1, l981.

BACKGROUND OF THE INVENTION

This invention relates to a method and apparatus for forming a flexible,reinforced plastic sheet material of indeterminate length and moreparticularly relates to forming a laminated plastic sheet material madefrom two films of a multi-layer thermoplastic material and a rectilinearweb of machine-direction (MD) and transverse-direction (TD) strands orfilms which are simultaneously laid down between the films.

Shipping sacks are used to store and ship 25-100 pound commodity lots ofmany diverse materials: for example, grain, cement, fertilizer, peatmoss, minerals, chemicals, plastic resins, etc. Bulk sacks are used forshipping and storing much larger quantities of many of these samematerials. Among the numerous component materials which are used forsuch sacks are single-ply 4-10 mil LDPE or LDPE/HDPE co-extruded filmand cross-laminated MD-oriented HDPE film. Reinforced composite sheetsare also available for such sacks, as described, for example, in U.S.Pat. No. 4,161,559.

Other uses for reinforced composite sheets are coverings forgreenhouses, barns, buildings under construction, and commodities whichmust be stored in the open. The reinforcing material may be in the formof a non-woven or pre-woven scrim or woven mesh material having openingsbetween the strands that are wider in inverse proportion to the severityof the loads to be met. Such a reinforced composite sheet is describedin U.S. Pat. No. 3,616,130.

Methods for producing reinforced composite sheets include the layeringof a scrim between a pair of flexible films (U.S. Pat. Nos. 3,186,893;4,088,805; and 4,106,261) and the formation of a woven or non-wovenpattern of MD and TD fibers simultaneously with or immediately prior tothe layering operation (U.S. Pat. Nos. 1,914,801; 3,169,087; 3,272,679;3,414,453; 3,496053; 3,511,739; 3,686,062; and 3,950,583).

Non-woven patterns may be sinusoidal (U.S. Pat. No. 1,914,801), MD/TDgrid (U.S. Pat. No. 2,851,389), or helical (U.S. Pat. Nos. 3,169,087;3,272,679; 3,332,823; and 3,332,824). Apparatuses for forming suchnon-woven patterns include the following diverse arrangements: (a) anendless reciprocating tape and guide bar arrangement for forming acyclically deposited web (U.S. Pat. No. 3,272,679); (b) a rotaryapparatus for winding a helix of strands around a pair of endlesscarriers having opposed and substantially parallel reaches (U.S. Pat.Nos. 3,332,823 and 3,332,824); (c) a horizontal rotary drum mountedabove a rotating table at the top end of a post carrying plastic strandsfor making laminated webs of filamentary reinforcing material (U.S. Pat.No. 3,414,453); (d) a positioning plate for moving warp strands undertension imparted by creel-and-tension carts about the surface of acylindrical support while adhesively coated fill strands are wound aboutthe warp strands to form a tubular web of fabric (U.S. Pat. No.3,496,053); (e) a plurality of strand guide bars carried by areciprocating tape and operated simultaneously in reciprocatingmovements, with a phase shift of 180° between the guide bars, to producean array of reinforcing strands having a sinusoidal configurations withmultiple overlap patterns (U.S. Pat. No. 3,511,739); and (f) a fixedcreel containing reels in two parallel rows making a first lap of warpthreads, a rotary creel containing a series of reels spaced apart aboutthe circumference of a coaxial circle, an elongated comb fordistributing the warp threads into a plane, a circular plate for windingthe weft threads into an annular lap in flattened spirals about the lapof warp threads, and cutters for opening up the annular lap (U.S. Pat.No. 3,950,583).

Co-axially extruding two different thermoplastic materials from a singleannular extruder die to form a duplex film by the blown tube method isdescribed in U.S. Pat. Nos. 3,223,761 and 3,467,565. Variouscombinations of polymers and co-polymers in multi-layered duplex plasticsheets, having differing melting points in the inner and outer layersfor bonding by heat and pressure to a web of reinforcing materialtherebetween, are described in U.S. Pat. No. 3,616,130.

Many of these processes produce composite sheet materials havingexcellent strength properties, but the materials have such excessivethicknesses or the processes operate at such slow speeds or areafflicted with so many maintenance or adjustment problems that costs areexcessive. In consequence, shipping sacks made from plastic film havethus far been utilized in a small fraction of the shippingsack/packaging business.

Accordingly, a thinner composite sheet having adequate strength andother physical properties at a basis weight that is at least 30% lessthan the weight of presently available composite sheets is needed.

A simpler on-machine method and an apparatus for forming a reinforcinggrid and for bonding the grid to the film on either side thereof to formthe thinner composite sheet at lower cost are equally needed.

Additionally, a method of bonding this novel sheet along the edgesthereof to form a tubular article, in order to retain the desirableproperties of central portions of the sheet, is also desirable in orderto obtain shipping sacks with uniformly suitable properties.

It is therefore an object to provide a composite film sheet ofindeterminate length, having a selectively high strength at a basisweight which is approximately 30% less than that used in shipping sacksat the present time.

It is also an object to provide a composite film sheet comprising twofilms and a reinforcing grid in which the transverse-direction film iscontinuous, is in parallel reaches at a selected spacing between thereaches, and has 180° loops connecting the ends of the reaches anddisposed entirely within and between the films.

It is additionally an object to provide a grid of machine-directionfibers, having a selected first strength/weight ratio and a selectedfirst spacing between the filaments, and a single transverse-directionfiber which has a selected second strength/weight ratio and is disposedtransversely and adjacent to the machine-direction fibers as parallelreaches which: (1) are connected sequentially by loops, (2) have aselected second spacing between the reaches, and (3) are bonded to theMD fibers.

It is further an object to provide a fiber-reinforced composite filmsheet of indeterminate length, comprising a pair of co-extruded filmsheets which are disposed in straddling relationship to the MD fibersand TD fibers so that each film sheet comprises an outer layer having alow softening temperature, whereby the pairs of film sheets, the MDfibers, and TD fiber are bonded together under heat and pressure.

It is still further an object to provide a fiber-orienting aparatus forcontinuously forming a single fiber into a plurality oftransverse-direction reaches which are connected at the ends thereof by180° loops.

It is also an object to provide an apparatus for continuouslyjuxtaposing a pair of films, the machine-direction fibers, and thelooped transverse-direction fiber into a sandwich.

It is another object to provide a means for removing the loops from thefilm-orienting apparatus without displacement of the loops andtransverse-direction reaches within the film sheets.

In accordance with these objectives and the principles of thisinvention, a composite film sheet of indeterminate length, having aselectively high strength at a basis weight which is approximately 50%less than that used in shipping sacks at the present time, is provided.This composite film sheet comprises:

A. MD fibers having a selected first strength/weight ratio and aselected first spacing between the fibers;

B. a single TD fiber which has a selected second strength/weight ratioand is disposed within the composite film as parallel reaches which:

(1) are connected sequentially by loops,

(2) have a selected second spacing therebetween, and

(3) are disposed transversely to the MD filaments; and

C. a pair of co-extruded film sheets which are disposed in straddlingrelationship to the MD fibers and the TD fiber so that the loops areenclosed between the film sheets, each film sheet comprising an outerlayer having a high softening temperature, and an inner layer having alow softening temperature, whereby the pairs of film sheets, the MDfibers, and the TD fiber are bonded together under heat and pressure.

Preferably, the film sheets are co-extruded, and the inner layers arebonded to both the MD fibers and the TD fiber. If necessary in aparticular combination of fiber and film compositions, an adhesive isadded to the fibers. It is particularly suitable that such an adhesivebe deposited on the MD fibers, such as by coating the fibers beforeusage thereof. However, it is further within the scope of the inventionto coat the film sheets and the TD fiber, alternatively or additionally.It is also a part of this invention to utilize fibers in the form ofco-extruded tape, having external layers of low-density polyethylene,whereby no adhesive is needed.

The continuous method of this invention for manufacturing a compositesheet material, having a combination of high strength properties andlight weight, comprises the following steps:

A. continuously drawing a plurality of machine-direction (MD) fibersfrom bobbins within a creel;

B. passing these MD fibers in longitudinally forward movement through acomb and forming a first planar lap of parallel, longitudinally alignedfibers;

C. drawing a single transverse-direction (TD) fiber from a bobbin at ahigh linear velocity;

D. passing this single TD fiber between spindles within an interweavingsection of a pair of endless, spindle-equipped chains whichcooperatively comprise the interweaving section, a diverging section,and a parallel section while revolving in opposite directions as a pairof planar patterns which are parallel to the first planar lap;

E. engaging the single TD fiber around the successively interweavingspindles of the spindle-equipped chains to form a successive pluralityof closely spaced loops when each spindle of one chain pulls the TDfiber toward and beyond the previously passing spindle of the otherchain;

F. laterally extending the single fiber, by longitudinal movement of theinward sides through the diverging section, to separate transverselyalternate loops in the plurality of loops and form two rows of loops anda plurality of closed spaced TD fiber reaches which are transverselydisposed to the longitudinally aligned MD fibers and connected at endsthereof by the plurality of loops;

G. continuing to move the transversely disposed TD reaches and loopsthrough the parallel section of the pair of chains;

H. drawing a pair of films from a supply thereof;

I. forwardly passing the pair of films in straddling and parallelrelationship to the plurality of longitudinally extending fibers and theplurality of transversely disposed fibers;

J. converging the films, the TD reaches, and the MD fibers to form afiber/film sandwich;

K. edge sealing the sandwich along each edge but inwardly of theadjacent row of loops;

L. withdrawing the loops from the spindles;

M. transversely stretching the withdrawn sandwich;

N. laminating the longitudinally extending films, the transverselydisposed reaches and loops, and the pair of films to form the compositesheet; and

O. winding the laminated sheet.

The pair of films are suitably formed by slitting a flattened tube ofextruded film, drawn from a roll thereof as the supply of step H, at thesides thereof. If the roll of extruded film is on approximately the samelevel as the laminating apparatus, each of the films is passed over aturning bar, whereby the drawing of step H and the forwardly passing ofstep I are perpendicularly related. The films are transversely stretchedby passage through a lateral expansion means, after the turningoperation.

Laminating the fiber/film sandwich inwardly of the loops, for holdingthe transversely disposed TD reaches and the MD fibers in place withinthe sandwich, forms a laminated strip on each side of the sandwich. Suchstrip laminating is done by two pairs of opposed heated rolls.

The withdrawing of step L is performed by a pair of cams which lift theloops from the spindles. The transverse stretching of step M isperformed by transversely disposed rolls having frictional surfaces withrespect to the films. The laminating of step N is performed by a pair ofheated rolls.

The extruded film is suitably a co-extrusion of high-density andlow-density polyethylene. Preferably, the high-density polyethylene is25% of the film by weight, and the low-density polyethylene is adjacentto the fibers. The fibers are suitably coated with a pressure-sensitiveadhesive. The MD and TD fibers may be in the form of monofilaments ormay be MD-oriented polypropylene tape. Alternatively, polypropylene tapeis extruded with low-density polyethylene, whereby lamination between MDand TD fibers and between the fibers and the film requires no adhesive.

The fiber-reinforced film sheet of this invention generally comprises anon-woven fiber network which is laminated between two layers ofco-extruded plastic film. The machine-direction fibers suitably consistof five hundred-denier (0.050-inch wide by 0.002-inch thick) orientedpolypropylene tape. The fibers are disposed a suitable distance apartwithin the first planar lap. This distance apart is in accordance withthe strength required for end use of the film sheet. For example, theymay be 0.375 inch apart, on centers. The transverse-direction fiber isdisposed in a serpentine form, with adjacent reaches of the fiberdisposed 0.375-inch apart, also measured on centers, as an exemplarydistance apart. The three-eighths inch spacing between MD and TD fibersis one specific example which is widely useful, but many other spacingsare feasible and highly suitable for particular applications. The MDfibers and the TD fiber are generally both polypropylene. Polypropylenetape is one highly satisfactory embodiment, but monofilaments andmulti-filaments of polypropylene and other high strength polymers can beused to form specific products having certain desired properties.

Polypropylene in the form of tapes, fibers, and filaments which areoriented in the machine-direction for optimum strength properties arewell known. When in the form of a single homogenous product that isextruded and drawn from a round die orifice, a monofilament is producedwhich has high strength (75,000 psi) and medium cost. When extruded froma flat die and slit into narrow widths in the machine-direction and MDoriented, polypropylene tape is produced, having medium strength (50,000psi) and low cost. This type of polypropylene fiber is the most widelyused in the textile industry at the present time. When extruded from amultitude of fine holes (spinerette) and spun into the finished yarn, amulti-filament strand is produced which has a number of fibers in thestrand (e.g.,50), producing a yarn of conventional appearance, muchgreater flexibility than the monofilament, and wider usefulness inregular textile applications. This product has medium strength (45,000psi) and a higher price than either the monofilament or thepolypropylene tape.

The tubular co-extruded film is 1.5 mil thick and comprises 25%high-density polyethylene (HDPE) and 75% low-density polyethylene(LDPE). The collapsed tube is slit at the sides or edges to form thepair of single-layer films. In addition to polyethylene as the rawmaterial for the co-extruded film, liquid or gas barrier materials, suchas nylon and films of heavier gauges or lighter gauges, are useful.

A suitable apparatus for manufacturing the fiber reinforced or compositefilm sheet of the invention comprises:

A. a machine-direction multi-fiber feeding assembly;

B. a transverse-direction single-fiber feeding assembly;

C. a fiber-orienting means for forming the single fiber into a pluralityof transverse-direction reaches which are connected by loops at the endsthereof and move in the machine direction at the same speed as do themachine-direction fibers;

D. a film feeding assembly for a pair of co-extruded films ofindeterminate length which are arranged in straddling relationship tothe MD and TD fibers;

E. a converging assembly for the machine-direction andtransverse-direction fibers and the pair of films to form a fiber/filmsandwich;

F. a high-temperature nip roll system for laminating the fiber/filmsandwich together to form the fiber-reinforced film sheet; and

G. a winder for winding the laminated fiber-reinforced film sheet into aroll.

The apparatus further comprises:

A. a pair of expander rolls for smoothing and widening the pair of filmsin the transverse direction, prior to reaching the converging assembly;and

B. an edge sealing assembly for heat sealing the pair of co-extrudedfilms of the sandwich to the transverse-direction reaches within a pairof strips which are disposed close to the loops at each edge butinwardly of the loops, whereby the fiber/film sandwich is conjoinedwithin the two strips.

This fiber-orienting means is an apparatus comprising a pair of endlessroller chains which are disposed to revolve in a pair of elongatedpatterns within a common plane. The opposed portions of the patternsmove forwardly and comprise an interweaving section, a divergingsection, and a parallel section. Each roller chain comprises a triplestrand of linked rollers and a row of spindles which are attached to butare laterally offset from the rollers to project outwardly from thepattern.

Each triple strand roller chain comprises pin link plates, roller pins,straight lug link plates, spindle arms attached to the straight lug linkplates, and spindles which are rotatably attached to each arm. Eachspindle comprises a spindle body having a convex groove for tracking theTD filament. The groove has a crown angle at its center of about 5°. Thespindle body further comprises a tapered fiber lift-off surface havingan angle of about 45° to the axis of the spindle.

The fiber-orienting apparatus, for producing the TD fiber reaches andloops, more specifically comprises a pair of endless roller chainassemblies which each comprise:

(1) a triple-strand roller chain,

(2) a row of chain attachment plates,

(3) a row of spindle arms, each arm being riveted at one end to one ofthe attachment plates and extending transversely to the roller chain,

(4) a row of spindles, each spindle being attached to the other end of aspindle arm, and each spindle comprising:

(a) a central screw and nut which are attached to the arm,

(b) a spindle shaft which coaxially surrounds the screw,

(c) a pair of spindle bearings surrounding the shaft, and

(d) a spindle body having a fiber-supporting portion and a taperedlift-off portion.

The chain system comprises a plurality of spindles lying within a commonplane on which the loops are held. For lifting each row of loops fromthe spindles after passing the edge sealing assembly , a cam means isprovided in cooperation with an overlying idler roll which enables thenip rolls to function as an elevating means for directing the fiber/filmsandwich obliquely to the common plane in which the spindles revolve.

Two pairs of edge pulling brushes and two pairs of short Mt. Hope rollsare also incorporated into the apparatus in order to stretch thefiber/film sandwich in the transverse direction before reaching thehigh-temperature nip roll system.

The method for making this fiber-reinforced composite film sheet and theapparatus for carrying out this method are both inherently flexible. Themethod has flexibility s to adjustable width of the composite filmsheet, for example, because the apparatus includes means for selectivelymoving the pairs of bushing chain assemblies, nip roll systems, loopdisengagement devices, and edge pulling devices toward or away from eachother. To achieve this flexibility, the idler sprockets on the innerside of the chain loops, the converging assembly, the edge sealingrolls, the loop release cams, the edge pulling brushes, and thetautening rolls are all mounted on a pair of frame plates which aretransversely movable relative to the frame of the laminator for changingthe width of the composite film sheet without changing the overall pitchlength of the chain assemblies.

The method is also flexible as to construction features of the compositefilm sheet in order to achieve acceptable performance of a film/laminantbag in any specific application by tailoring the strength properties ofthe composite film sheet so that the bag can pass the requisiteperformance tests for its type, such as progressive drop, 6-sides drop,and creep. Such construction flexibility can be obtained by using fiberscontaining various desired proportions of high- and low-densitypolyethylene, polypropylene, polyamides, polyesters, polystyrene,polyacrylonitriles, polyvinyl chloride, rayon, cotton, wool, and othersynthetic and natural fibers, including copolymers, and the like. Thedenier of the fibers, the center-to-center spacing therebetween, and theadhesive for bonding MD fibers to TD fibers and for bonding both fibersto the films can also be varied. In addition, low-density polyethylenecan function as a heat-activated adhesive if co-extruded as the outerlayer for a polypropylene fiber core. Further flexibility ofconstruction can be obtained by varying the type of polymer, itscrystallinity, the thickness of the films, and the proportions ofpolymer types if a layered film construction is selected, such as 25%high-density polyethylene and 75% low-density polyethylene.

The film sheet of the invention may be converted into a tube either bysewing or by hot-melt gluing along the edges, provided that there issufficient overlapping that the rows of filament loops are in overlyingrelationship to provide a seam having the equivalent strength of thebody of the laminate. This tube may then be fed to a bag-makingoperation which can produce bags of desired sizes and strengthproperties by sewing or gluing along the bottom and top edges of thebags.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of the entire apparatus for making afilament-reinforced film sheet.

FIG. 2 is a right side elevation of the apparatus seen in FIG. 1, takenon the lines 2--2 in FIG. 1.

FIG. 3 is a side elevation of the film feeding assembly and laminator ofFIG. 1, looking in the direction of the arrows 3--3 of FIG. 1.

FIG. 4 is a schematic plan view of the fiber and film feeding,converging, and laminating portions of the apparatus, as seen in FIG. 1.

FIG. 5 is a right-side elevation of the fiber and film feeding,converging, and laminating operations of the apparatus, looking in thedirection of the arrows 5--5 in FIG. 1, with the roller chain assembliesremoved.

FIG. 6 is a transverse elevation, partially in section, looking in thedirection of arrows 6--6 in FIG. 4.

FIG. 7 is a plan view of a portion of the chain system which shows theinterweaving section, the diverging section, and a portion of theparallel section thereof, showing the TD fiber being drawn into theweaving section, spread into transverse TD reaches in the divergingsection, and moving in the machine direction in the parallel sectionthereof.

FIG. 8 is a sectional elevation of a single spindle as seen in plan viewin FIG. 7.

FIG. 9 is a transverse sectional elevation through the apparatus ofFIGS. 1 and 2, looking in the direction of the arrows 9--9 in FIG. 4.

FIG. 10 is a machine-direction sectional elevation through the expanderrolls and converence assembly of the apparatus, looking in the directionof arrows 10--10 in FIG. 4.

FIG. 11 is a transverse sectional view, showing the convergence assemblyfor the fibers and films, looking in the direction of arrows 11--11 inFIG. 4.

FIG. 12 is a sectional elevation through the edge sealing assembly alongthe right side of the machine, showing the two layers of film and loopsof TD fibers therebetween over the spindles, just beyond the nip of theheat sealing rolls.

FIG. 13 is a perspective view of an engagement support stand for theincoming TD fiber.

FIG. 14 is a perspective view of a cam used for lifting the loops fromthe spindles.

FIG. 15 is a fragmentary plan view of a small section of the chain onthe right side of the machine which shows the cam partially beneath theidler roll beneath which the film sandwich passes.

FIG. 16 is a side view of the idler roll, cam, and spindles, as seen inFIG. 15.

FIG. 17 is an end view of the idler roll, release cam, and spindle,showing a filament loop that has been released from its spindle.

FIG. 18 is a plan view of a portion of a filament-reinforced compositefilm sheet (for brevity, sometimes called a fiber/film laminate), aftermanufacture in the apparatus of FIGS. 17.

FIG. 19 is a plan view of a lap seam which is formed by overlappingopposite edges of a fiber-reinforced composite film sheet and by sealingwith two strips of hot melt adhesive so that the loops along theopposite edges coincide with each other.

FIG. 20 is a sectional elevation view of the lap seam shown in FIG. 19,looking in the direction of the arrows 20--20 in FIG. 19.

FIG. 21 is a plan view of an auxiliary spindle drive which is mountedalong the inner side of a rollerchain within the diverging sectionthereof.

FIG. 22 is a sectional elevational view of the auxiliary spindle driveof FIG. 21, looking in the direction of the arrows 22--22 in FIG. 21.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention may be more fully understood by referring to the drawingsin which a useful and operably satisfactory embodiment is shown.

1. Description of the Apparatus

The apparatus of the invention for manufacturing a fiber-reinforcedcomposite film sheet comprises a machine-direction multi-fiber storageand feeding assembly 20, a transverse-direction single-fiber storage andfeeding assembly 50; a chain system 80,80' for forming the single fiberinto a plurality of transverse-direction reaches which are connected byloops at the ends thereof and moved sidewise in the machine direction atthe same speed as the machine direction fibers; a film storage andfeeding assembly 100 for supplying a pair of co-extruded films ofindeterminate length; a film turning and expanding assembly 120 foraligning and sidewise expanding the films; a converging assembly 130 forarranging the machine-direction and transverse-direction fibers and thepair of films to form a fiber/film sandwich; an edge-sealing assembly150 for heat sealing the pair of co-extruded films to the transversedirection reaches within a strip which is disposed close to the loops ateach edge but inwardly of the loops, where by the fiber/film sandwich isconjoined within the strips; a film pickup assembly 160 which includes acam means for lifting each row of loops from the spindles after passingthe edge sealing assembly 150 and an elevating means for directing thefiber/film sandwich obliquely to its previous plane of movement; an edgepuller assembly 170 for smoothing the sandwich close to its edges andsidewise tautening the sandwich while it continues to move obliquelyupwardly; a laminating assembly 180 for heat sealing the co-extrudedfilms, MD fibers, and TD fiber together, whereby the sandwich isconverted into the fiber-reinforced composite sheet 200 of theinvention; and a winder 190 for winding the laminated fiber-reinforcedfilm sheet into a roll.

The machine-direction fiber storage and feeding assembly 20 is shown inFIGS. 1 and 2 and comprises a creel 21 supporting a large number of MDbobbins 23, a guide 22 on creel 21, an MD fiber break detector andstopping device 25, an eyeboard 29, an idler roll support 31, an upperidler roll 33, a lower idler roll 35, a first set of MD fiber guides 36,a third idler roll 39, and a second set of MD fiber guides 43.

The transverse-direction fiber storage and feeding assembly 50 comprisesa pair of TD fiber bobbins 51, which are supported on a support frame53, and a TD fiber first feed guide 55 which is also supported on frame53. Associated with TD fiber storage and feeding assembly 50 is a TDengagement support stand 64, shown in perspective in FIG. 13, comprisinga base 65 which is attached to such components of the apparatus frame asvertical members 48 and horizontal members 49, as seen in FIG. 2.Support stand 64 also comprises an upright support 66 which is attachedto base 65, a laterally adjustable member 67 and a longitudinal member68 which are attached to the top end of upright support 66, and avertically adjustable member 69 at the forward end of member 68. Member69 has jaw supports at its lower end for clamping a TD fiber eyelet 63which is made of ceramic and is at the same level as spindles 90. Eyelet63 is so positioned, as seen in FIGS. 6 and 7, that it is disposedbetween each spindle 90,90' and the roller chain assemblies 80,80' towhich the spindle is attached and is also exactly between the shafts ofidler sprocket 79 and drive sprocket 79', whereby it is at the pointwhere maximum intermeshing of spindles 90,90' occurs in order tointroduce TD fiber reach 57 between spindles 90,90' and above theirrespective arms 85,85'.

The apparatus further comprises a pair of chain drive and supportmechanisms 70,70' and a pair of roller chain assemblies 80,80' forpulling the TD fiber into transverse-direction reaches connected by 180°loops. The drive and support mechanism 70,70' for chains 80,80'comprises a drive sprocket 71' which is visible in FIG. 6, a pluralityof bearings 73,73', shafts 75,75', gears 77,77', two pairs of loop fiberrelaxation sprockets 78,78', three pairs of idler sprockets 76, andidler sprocket 79 and drive sprockets 79' at the point of intermeshing,as seen in FIG. 4. Sprockets 78 are also idler sprockets.

The pair of endless roller chain assemblies 80,80' each comprises atriple-strand roller chain 82,82' such as Browning A.S.A. No. 35-3 ofthe Browning Manufacturing Division of Emerson Electric Co., pin linkplates 81,81', roller pins 84,84', straight lug link plates 83,83' suchas Browning A.S.A. No. 3-2; spindle arms 85 which are each attached witha rivet to a link plate 83,83' and extend transversely to the verticalrow of rollers 82,82', wear strips 86 which are each attached to andunderlie a spindle arm 85, and spindles 90,90', each spindle beingattached to the outer end of an arm 85, as best seen in FIGS. 6, 7 and8. Each roller chain assembly 80,80' is arranged to revolve endlessly ina planar pattern that is slightly L-shaped so that the two chains incombination form a U, in plan view, which is open toward the dischargeend of the apparatus, as shown in FIG. 4.

Each spindle 90 comprises, as can be clearly seen in FIG. 8, a spindleshaft 91, a spindle retaining bolt 92, lock nut 94, a pair of spindlebearings 93, and a spindle body 95 comprising end portions 96, a taperedfiber lift-off surface 97, and a convex groove 98 for tracking the TDfiber. Angle 99 of the crown of groove 98 is about 5° , and the taperedfiber lift-off surface is at about 45° to the longitudinal axis of aspindle 90. Spindle shaft 91 and spindle bearings 93 coaxially surroundbolt 92, such that each spindle 90 is mounted for rotation about itsaxis (bolt 92).

Viewing FIG. 7 as spindles 90,90' revolve in clockwise andcounter-clockwise directions, respectively, it is readily apparent thatthey move inwardly past one another and leave a space therebetween whichpermits eyelet 63 to remain in place without contact with spindles90,90'. As spindles 90,90' continue to revolve, they move outwardly pastone another and leave interweaving section 87 just as they begin toengage the TD fiber which is leaving eyelet 63 to form initial TDreaches 58. Spindles 90,90' then move further apart in diverging section88 and finally move parallel to one another in parallel section 89 ofchains 80,80', with facing spindles 90,90' moving in the machinedirection, while forming TD reaches 59 which are connected by 180° loops141 over grooves 98.

An auxiliary spindle drive 230 is shown in FIGS. 21 and 22. An air motor231 is attached by a shaft to a drive rotor 233 which turns a drive roll235 having an elastomeric drive surface 237 which contacts the innersides of spindles 90. Air motor 231 is supported by a base 239 which isattached to an arm 238 and a bar mount 234 which is in turn supported bya clamp and bar support 236.

At least one auxiliary spindle 230 is mounted alongside each divergingsection 88, close to drive and support mechanisms 70,70'. Preferably,spindle 230 is disposed at spindle No. 5 (designating spindle No. 1 asbeing on the imaginary line connecting shafts 75,75'). A second spindle230, shown in phantom in FIG. 21, is sutiably disposed at spindle No.25. The spindles are driven by drive surface 237 at a somewhat higherspeed than the speeds imparted by the moving TD fiber.

With such a pair of auxiliary spindle drives 230 as helper drives forchains 80,80', a maximum speed of 10-12 feet per minute that wasobtained on the laminator at the maximum laminator width setting, ascompared to about 4-5 feet per minute with no helper drive. With twoauxiliary drives 230 along each diverging section, as shown in FIG. 21,a speed of 35 feet per minute has been achieved at the maximum widthsetting. It has been found that using a higher speed than these maximumspeeds breaks the fiber at its point of maximum tension which is at themaximum divergence point. Additional auxiliary drives 230 may beinstalled, or a plurality of elastomeric belt drives may be disposedalong the entire inner lengths of diverging reaches 88 to impartsequentially greater rotational speeds to spindles 90,90'.

Film storage and feeding assembly 100 comprises a roll support stand101, a dancer and slitter stand 102, three idler rolls 103 which aresupported on stand 102, a dancer idler roll 104 which is supported by acounter-weighted arm 105 which is pivotally attached to stand 102, fouridler rolls 106, 107, a pair of edge slitters 108, and anelectromagnetic unwinding brake 109, as may be seen in FIGS. 1 and 3.

Film turning assemblies 120 comprise a support member 121 and twoturning bars which are visible in FIGS. 1, 2, 3, 4, and 5 and aredisposed horizontally and at 45° to the machine direction. They areupper turning bar 123 and lower turning bar 125 which are attached tosupport 121. Associated with turning bars 123, 125 are a pair of idlerrolls and a pair of expander rolls for sidewise stretching of the upperand lower films 114, 115. These are an upper idler roll 126, an upperMt. Hope expander roll 127, a lower idler roll 128, and a lower Mt. Hopeexpander roll 129 which may be seen in FIGS. 4, 5, 9, and 10.

Convergence assembly 130 is attached, at each end thereof, to a widthadjustment plate 46 of the apparatus and comprises an upper edge plate131, a lower edge plate 132, side supports 133, and support members 139to which side supports 133 are attached. Plates 131, 132 each comprise apair of sliding members 134, having adjusting slots 135 and bolts 136,as shown in detail in FIG. 11. The lower edge 137 of plate 131 and theupper edge 138 of plate 132 are the functioning members of convergenceassembly 130 when upper and lower edge plates 131, 132 have beenproperly adjusted so that there is virtually no horizontal clearancebetween them, as indicated in FIG. 10.

Edge sealing assembly 150 comprises, as may be clearly seen in FIG. 12,an upper sealing roll 151, a lower sealing roll 152, a pair of gears153, a sprocket drive 154, a pair of siphon pipes 155, a pair of rotarycouplings 156 which are attached to siphon pipes 155 for circulating hotoil through the unit, and an air cylinder 157 for selectivelypressurizing rolls 151 and 152 and for vertically retracting roll 151from roll 152. The assembly is attached to and supported by a framemember 158 through width adjustment plate 46. Rolls 151, 152 containchannels 159 through which the hot oil is circulated from pipes 155.

Film pickup assembly 160 comprises a cam 161 which is visible inperspective in FIG. 14. Cam 161 comprises a ramp 162, a triangular ledge163, a top surface 166, and a rigidly attached clamp 165 for attachingcam 161 to a cylindrical support member. Film pickup assembly 160further comprises a pickup roll 164 which is disposed directly above cam161 so that there is barely sufficient clearance for sliding passage ofthe edge-laminated sandwich 140 between surface 166 and roll 164, asseen in FIGS. 15-17.

Edge puller assembly 170, as seen in FIG. 5, comprises two pairs ofcounter-rotating brushes 171, 173, two pairs of short Mt. Hope rolls176, and support stands which are attached to width adjustment plates 46but are not visible in the drawings. Brushes 171, 173 have frictionalsurfaces which enable them, when counter-rotating, to engage the upperand lower surfaces of the film sandwich and pull the outer edges 148away from each other, thereby smoothing strips 145, 147. Rolls 176 keepthe entire sheet in taut condition across its surface before it entersthe laminator.

Laminating assembly 180 comprises an upper heater roll 181, a lowerheater roll 183, a frame 185 by which rolls 181, 183 are rotativelysupported, a pair of air cylinders 187 which control the nip pressurebetween rolls 181, 183 and separate rolls 181, 183 for thread up ofincoming sandwich 140, and an idler roll 189 which is adjustablypositioned on a support 186.

Winder assembly 190 comprises a fram 191, an axle 195, and a drive 193,as seen in FIGS. 1 and 2. A roll 197 of the fiber-reinforced compositefilm is wound on axle 195 as the apparatus operates.

2. Operation of the Apparatus

In the apparatus shown in FIGS. 1-17, the fiber-reinforced compositefilm sheet of the invention is formed in four basic steps which are asfollows:

A. forming a machine-direction (MD) multi-fiber planar lap 37 by:

(1) continuously drawing a plurality of machine-direction (MD) fibers 27from a plurality of bobbins 23, passing these MD fibersin longitudinallyforward movement through a guide 22 and eyeboard 29 to converge the MDfibers vertically and spread them horizontally, thereby forming a firstplanar reach 37 of parallel, longitudinally aligned MD fibers afterpassing through a guide 36, and

(2) moving the MD fibers obliquely upwardly as climbing reach 41 andconverging reach 45 to reach convergence assembly 130 and become part ofsandwich 140;

B. forming a transverse direction (TD) single-fiber planar lap by:

(1) drawing a single TD fiber from bobbins 51 at a high linear velocity,

(2) passing this single TD fiber between spindles 90,90' of a pair ofendless, spindle-equipped chains 80,80' which cooperatively comprise aninterweaving section 87, a diverging section 88, and a parallel section89 while revolving in opposite directions as a pair of planar patternswhich are parallel to the first planar lap,

(3) engaging the single TD fiber 52 around the successively interweavingspindles 90,90' of the spindle-equipped chains 80,80' to form asuccessive plurality of closely spaced taut loops 141 when each spindleof one chain 80,80' pulls the TD fiber toward and beyond the previouslypassing spindle of the other chains 80',80, and

(4) laterally extending the single fiber 52, by longitudinal movement ofchains 80,80' through diverging section 88, for transversely separatingloops 141 and forming two rows of loops connecting a plurality ofclosely spaced TD fiber reaches 58 which are transversely disposed tolongitudinally aligned MD fibers 37, and

(5) continuing to move the TD fiber as transversely disposed TD reaches59 and loops 141 of a second planar lap through parallel section 89 ofthe pair of chains 80,80' and into convergence assembly 130 (see FIGS. 7and 10);

C. straddling the MD and TD laps with a pair of films to form a sandwich140 by:

(1) drawing a flattened tube from a supply 111 therefor and cutting itsopposite edges with edge cutters 108 to form a pair of films 114, 115,

(2) forwardly passing the pair of films 114, 115 as reaches 116, 117 instraddling and parallel relationship to TD fibers 58 and MD fibers 41(see FIG. 5), and

(3) converging the films as reaches 118, 119 toward TD reaches 59 and MDfibers 45 to form a fiber/film sandwhich 140 at convergence assembly130; and

D. laminating sandwich 140, to form the film-reinforced composite sheetof the invention in roll form, by:

(1) edge-sealing sandwich 140 within narrow strips 146 (see FIG. 15),close to each side edge 148 but inwardly of the adjacent row of loops141 means of edge sealing assembly 150,

(2) withdrawing taut loops 141 from spindles 90 by means of apparatus160 to form relaxed loops 143,

(3) transversely smoothing and stretching the withdrawn sandwich 140 bymeans of edge pulling assembly 170,

(4) laminating sandwich 140, consisting of longitudinally extendingfibers 45, transversely disposed reaches 59, released loops 143, and thepair of films 118, 119, to form the composite sheet 200 by means oflaminating assembly 180, and

(5) winding the laminated sheet composite into roll 197 by means ofwinder assembly 190.

More specifically, a plurality of MD fibers 24 are drawn from bobbins23, passed horizontally through guide 22 and break detector 25 andconvergingly into eyeboard 29, over idler rolls 33, 35, through set ofMD fiber guides 36, and horizontally in the machine direction asparallel reaches 37. As best seen in FIGS. 5 and 10, horizontally movingMD fibers 37 then pass beneath idler roll 39, move obliquely upwardly asreaches 41, go through fiber guides 43, climb more gradually as MDconverging reaches 45 in adjacent relationship with lower film 119, andform a part of a sandwich 140 at convergence assembly 130.

The single TD fiber 52 is pulled at a high velocity alternately from thepair of bobbins 51, which are disposed outside of the compositesheet-forming apparatus, through first guide 55. As seen in FIGS. 2 and13, fiber 52 is then passed obliquely beneath turning bar 123 and aboveMD fibers 37 as reach 54, then through second TD fiber guide 62 to TDfiber eyelet 63 while moving at an angle to the horizontal of about 20°as descending reach 57 to pass over revolvingly approaching spindles90,90' which are attached to the pair of chains 80,80'. Immediatelyafter leaving eyelet 63, the TD fiber is between the interwoven spindles90,90' and the respective roller chains 82,82', as seen in FIGS. 5, 6,and 7, within interweaving section 87 of chains 80,80'. As spindles 90revolvingly disengage from each other in the initial part of divergingsection 88, the TD fiber begins to be pulled into lengthening reaches 58throughout diverging section 88. Then, throughout parallel section 89,reaches 59 of uniform length are formed, each reach 59 being closelyspaced and connected at each end by a taut loop 141 around one ofspindles 90,90' to the succeeding and preceeding reaches 59.

Fiber 52, as wound on bobbins 51, is suitably coated with a very thinlayer of heat-activated adhesive. The preferred fiber-film adhesive is521 GH of Morton Chemical Co., which is applied as a 2% by weight solidsolution, using trichloroethane as solvent. This solution is applied onboth sides as 21% by wet weight of the fiber and is dried throughlybefore winding onto TD fiber bobbins 51. There is no adhesive actionuntil heat is applied, the coated fiber 52 being fairly slippery overconvex surfaces 98 of spindles 90.

Fiber loops 141 are shown in FIG. 12 as sandwich 140 is passing throughedge sealing assembly 150. With reference to the right side of theapparatus which is principally illustrated in the drawings, these loops141 are lifted from spindles 90 by cams 161 while chains 80,80' areslightly approaching one another, as best seen in FIG. 4, while movingpast relaxation sprockets 78,78', and as the edge-sealed sandwich ispassing beneath idler roll 164 of sandwich pickup assembly 160. Althoughthe released loops 143 and outer edge portions of films 145, 147 droopover ledge 163 of cam 161 and tend to hang down while entering reach 167during upward travel toward laminating assembly 180, as seen in FIGS. 16and 17, they are smoothed and pulled outwardly by edge pulling assembly170, as seen in FIG. 5.

As seen in FIG. 3, the collapsed tube of coextruded film is pulled froma roll 111 on film support stand 101 and passed over first idler roll103 to a tension adjusting means comprising counter-weighted arm 105,which is pivotably supported on dancer and slitter stand 102, and danceridler roll 104. The flattened tube therefore leaves roll 111, passesover first idler roll 103, dancer idler roll 104, and second idler roll103, whereby tension may be sensed and vertical tensioning reaches 112may be adjusted by movement of arm 105. The flattened roll of film thenpasses under third idler roll 103 to edge slitters 108 as horizontalreach 113. The edges of the tube are slit in each apparatus 108 to formupper and lower films. The upper film then passes under and over rolls106 to form upper reach 114, and the lower film passes over and underrolls 107 to form lower reach 115. Both reaches 114, 115 pass throughfilm turning assemblies 120.

Specifically, as seen in FIG. 5, the upper film passes over and thenunder upper turning roll 123 and leaves as reach 116 which is orientedat 90° to reach 114. The upper film then passes over idler roll 126 andunder expander roll 127 as slightly descending reach 118. The lower filmpasses under and then over turning roll 125 and proceeds as reach 117 tolower idler roll 128 and then over expander roll 129 as slightlyascending reach 119. The relationship of the lower film in reaches 117and 119 to idler roll 128 and expander roll 129 may also by clearlyviewed in FIG. 10.

Returning to FIG. 5, film reaches 118, 119, MD fiber reaches 45, and TDfiber reaches 59 converge into a single sandwich 140 at convergenceassembly 130 which is shown in section in FIG. 10 and in front elevationin FIG. 11. The films and fibers pass through the slot formed by theseparated plates 131, 132, beneath lower edge 137 and above upper edge138, respectively, of edge plates 131, 132 to form a closely juxtaposedsandwich 140 which proceeds to edge sealing assembly 150, as seen inFIG. 12.

Operation of edge sealing assembly 150 creates a thin seal strip 146along edge of sandwich 140 but inwardly of tensioned loops 141 which arearound spindles 90. A seal strip 146 is visible in FIG. 15.

Consulting FIG. 2, it is apparent that sandwich 140 moves from edgesealing assembly 150 to film pickup assembly 160 which is shown indetail in FIGS. 14-17. Chain assemblies 80,80', as shown in FIGS. 1 and4, move slightly inwardly toward each other while passing betweenrelaxation sprockets 78,78'. At this point, cams 161 are beneathsandwich 140 and idler roll 164 is directly thereabove. The relaxedsandwich 140 is then lifted on each side by ramp 162 of each cam 161 sothat relaxed loops 143 are progressively lifted past tapered lift-offsurfaces 97 of spindles 90, while passing over top surfaces 166 of cams161 and while being progressively raised by outwardly sloping ledges 163of cams 161, until they hang down between edge film strips 145,147, asseen in FIGS. 16 and 17. Cams 161 and relaxation sprockets 78,78'therefore function, in combination, as loop disengagement devices fortaut loops 141, and roll 164, in combination with the elevated positionof laminating assembly 180, functions as a pick-up device for sandwich140, whereby the edge-sealed film sandwich can travel diagonallyupwardly as reach 167. As seen in FIG. 15 in combination with FIG. 5,while sandwich 140 moves obliquely upwardly as reach 167 toward thelaminator, edges 148 extend beyond relaxed loops 143.

En route to laminator 180, sandwich reach 167 is acted upon by edgepuller assembly 170 which is visible in FIG. 5. Counter-rotating brushes171,173 engage the outer portions of sandwich 140 and pull strips145,147, with relaxed loops 143 therebetween, outwardly whilestraightening out wrinkles in edge strips 145,147. Disposed along eachedge of reach 167, between brushes 171,173 and laminator 180, are a pairof short Mt. Hope rolls 176. These rolls 176 are visible only in FIG. 5.They are disposed at about 10° to the machine direction and tauten theentire sandwich 140 transversely, just before it enters laminatingassembly 180.

While passing through laminating assembly 180, the entire sandwich 140is softened by heat and pressure so that both films and both fibers arelaminated together between rolls 181,183 to form the integralfiber-reinforced composite sheet 200 which next passes under lower roll183 and over selectively positioned idler roll 189 to leave laminatingassembly 180 as reach 188 which then proceeds, as seen in FIGS. 1 and 2,to winding assembly 190.

In winding assembly 190, reach 188 is wound into a product roll 197 of afiber-reinforced composite film sheet 200 which can be stored andprocessed as desired to make shipping bags and bulk bags of any requiredstrength and size characteristics. The width of sheet 200 can also beadjusted within selected limits without changing the overall pitchlength of chain assemblies 80,80'. Such flexibility for width adjustmentis an important requirement because of the varieties of bag widths thatare used in the shipping sack industry. To achieve this flexibility,idler sprockets 78,78' and 76,76' on the inner sides of chain assemblies80,80', each end of convergence assembly 130, each pair of edge sealingrolls 151,152, each loop release cam 161, each pair of edge pullingbrushes 171,173, and each pair of Mt. Hope tautening rolls 176 are allmounted on a single pair of horizontally and longitudinally disposedframe plates 46 which are slotted and adjustably attached to horizontalframe members 46 by bolts 44. The width adjustability that is achievableby sideways movement of these plates 46 can best be understood byreferring to FIGS. 9, 11, and 12.

The four edge sealing rolls 151,152 and the upper and lower laminatingrolls 181,183 are generally heated by a hot oil system which utilizes aheating oil such as Dowtherm A. A suitable heating and circulatingsystem for this material comprises a storage tank containing theDowtherm A, a pump for circulating it, a heater, and a piping system forpassing it through the heater into all four edge sealing rolls inparallel, into the laminating rolls in series, and back to the tanks.The system operates at about 30 psi. The edge sealing rolls are eachabout 12 inches in diameter and about two inches in width.

The resulting fiber-reinforced composite film sheet 200 is shown in FIG.18 in plan view. MD fibers 201, TD reaches 203, TD loops 205, and bothfilms 207 form a selectively strong product having one-fourth theweight, much greater water resistance, improved tear and impactproperties, and greater grease resistance as compared to a comparableproduct of paper construction. This composite sheet also has one-halfthe weight, the ability to utilize a sewn closure, breathability at thecost of minimal loss of strength, better strength and tear properties,more stiffness with no opening problems, hot filling capabilities,grease-proofness, and better resistance to finger puncture as comparedto comparable products of plastic construction.

These comparisons are made for a fiber-reinforced composite film sheethaving a total average thickness of 2.5 mil, utilizing 0.25 milhigh-density polyethylene and 0.75 mil low-density polyethylene incombination with 500 denier polypropylene tape as both machine-directionand transverse-direction fibers. This composite film sheet derives apart of its novel strength properties from the 180° loops 205 beingentirely within and between the films 207 whenever its usage requiresconjoining the edges of a single sheet as a lap seam to obtain greaterwidth, as for making a bulk bag, or to produce a tubular bag, such as ashipping bag.

3. Manufacture of a lap seam.

Such a lap seam 210, with loops 215,225 in overlapping relationship, isshown in plan view in FIG. 19 and in section in FIG. 20. MD fibers 211form a grid with TD reaches 213, and both fibers 211,213 are between andlaminated to films 217,219 of the upper composite film sheet. MD fibers221 form a grid with TD reaches 223, and both fibers 221,223 are betweenand laminated to films 227,229 of the lower composite film sheet. Loops215 are inside edges 218 of upper films 217,219, and loops 225 is PG,34inside edges 228 of lower films 227,229. Loop overlap 224 is generallyabout 1.0-1.5 inches and preferably about 1.0 inch. Edge overlap 226 isgenerally 1.5-2.5 inches, preferably about 1.5 inches. Adhesive strips216 are between films 219,227 and substantially coincide with loops215,225.

4. Manufacture of shipping bags.

The fiber-reinforced composite film sheet or fiber/film laminate 200 ofthis invention is believed to be a bag-making material havingexceptional design flexibility for meeting a very wide variety of marketneeds. A number of diverse bags are accordingly manufactured and testedto meet such needs by forming various selected fiber-reinforcedcomposite film sheets of the invention into tubes of indefinite length,having lap seams as illustrated in FIGS. 19 and 20. The tubes are thencut into required lengths and sewn at bottom and at top ends afterfilling with selected test materials, as described in the followingexamples.

EXAMPLE 1

Bags made of 3 ply-50 lb. paper and 5 to 6 mil low density polyethylene(LDPE) are used in the marketplace for shipping and selling 50 lbs. ofsuch squashy products as mulch and some fertilizers. A fiber/filmlaminate bag is produced from a 2.5 mil fiber/film composite sheet 200which is formed from 2 sheets of 1 mil film, reinforced in bothdirections with 500 denier polypropylene (PP) fiber, by using hot-meltadhesive to conjoin sides thereof as a lap seam 210. The product isestimated to be satisfactory in its general characteristics for thisuse.

EXAMPLE 2

The 2.5 mil bag of Example 1 is tested with 50 lbs. of granularpolyethylene (PE) resin. The results are unacceptable in the 6-side droptest because the drop performance is merely 4 feet.

The bag is then manufactured with a fiber/film laminate made of 500denier MD fibers and 1000 denier TD fiber. The drop performanceincreases from 4 feet to 8 feet, making the bag satisfactory for theresin market currently served in Europe by 8-9 mil PE bags and by 5 plypaper bags in the U.S. (one of the plys may be polyethylene).

EXAMPLE 3

Among 30 different mixes marketed by a large regional feed supplier,whole corn is regarded as the most difficult feed material to packagesafely. Fiber/film laminate bags are manufactured with 500 denier MDfibers and 1000 denier TD fibers. The edge drop distance is 3 feet andis unacceptable.

The bag is then manufactured with 1000 denier polypropylene fiber in theMD direction, and the resulting bag has an edge drop performance of 5feet which is an acceptable height. This bag, comprising two 1-mil filmsplus 1-mil polypropylene fibers, is able to compete with a 4-milall-polypropylene woven fiber bag for handling 100 lbs. of white corn.

EXAMPLE 4

In the initial concept of the fiber/film laminate bag, it was felt thatthe loops at the laminate edge would add to the strength of the lap seambecause in the event of a seam failure, each loop must pull through orout of the heat-sealed sandwich and thus should add to the overallstrength of the lap seam. There are more variables involved than simplyloops vs. no loops; for example, fiber-to-film bond strength and theweight of hot melt adhesive used to form the loop seam have an importanteffect on overall seam strength. Furthermore, the type of hot-meltadhesive can make an important difference.

Referring hereinafter to FIGS. 19 and 20, a lap seam 210 is preparedfrom a fiber-reinforced composite film sheet made from co-extruded films217,219,227,229 co-extended from 80% low-density polyethylene(polyethylene 682 of Dow Chemical Co.) and a blend of 14% high-densitypolyethylene (polyethylene TR 130 of Phillips Petroleum Co.) and 6%polybutylene. The fiber/film laminate is prepared by placing thelow-density polyethylene adjacent to fibers 211,221. The hot meltadhesive used for adhesive strips 216 is Munel 610 hot melt adhesive ofGulf Oil Co. The fiber-to-film bond strength is 5 lbs. per fiber inch ofshear surface. TD fibers 213,223 are 0.375 inch apart, measured oncenters.

Test samples are prepared by cutting one-inch wide strips from lap seam210 in which the TD fibers are 3/8" apart. All testing is done with twofibers in each lap of the seam by selective cutting of the test samplesto provide an enclosed loop between the two fibers. In the case wherethe loops of each sample side are offset, the sample is cut to providetwo TD fibers on one side and three TD fibers on the other side. Theloops have a one-inch overlap in the transverse direction.

The one-inch wide test samples are placed between the jaws of a tensiletesting machine recording both stress and strain, with two inches ofsample length exposed between the jaws. The results are given in thefirst line of Table I.

Nine samples are then cut from a lap seam 210 made with the same hotmelt adhesive and the same film and fibers but with a different fiberadhesive furnishing 6.8 lbs. of bond strength per fiber inch of shearsurface and with no loops within the same area. The results are given inthe second line of Table I.

                  TABLE I                                                         ______________________________________                                        Ex-             Bond                                                          ample Loops/    Strength,                                                                              Break Force, Lbs.                                                                        Elong. at                                 No.   No Loops  Lbs.     --χ                                                                            σ                                                                            η                                                                              Break, Inches                         ______________________________________                                        4     Loops     5        11.6 1.8  9    0.64                                  4     No Loops  6.8       8.7 1.0  9    0.36                                  5     Loops     7.2      16.4 0.8  7    0.63                                  5     No Loops  8.1      17.2 0.9  10   0.69                                  6     Loops     9.3      17.8 1.3  6    --                                    6     No Loops  9.3      17.8 1.0  5    --                                    ______________________________________                                    

EXAMPLE 5

Another lap seam 210, made from coextruded film consisting of 80% ofpolyethylene 687 of Dow Chemical Co. and 20% of TR 130 high-densitypolyethylene of Phillips Petroleum Co., using a Goodrich hot meltadhesive and a fiber adhesive furnishing 7.2 lbs. bond strength for theloop samples and 8.1 lbs. bond strength for the samples without theloops, is similarly tested with the results as given in the third andfourth lines of Table I.

EXAMPLE 6

An additional lap seam 210, made from co-extruded film consisting of 80%low-density polyethylene 682 of Dow Chemical Co. and 20% of TR 130 ofPhillips Petroleum Co., using Gulf 610 as a hot melt adhesive and anadhesive coating on the fibers which furnishes 9.3 lbs. of bond strengthper fiber inch of shear surface, is similarly tested. The results aregiven in the fifth and sixth lines of Table I.

The conclusions from these tests of Examples 4-6 are as follows:

(1) With a low fiber-to-film strength (5 lbs. per fiber inch of shearsurface), loops add approximately 30% to the force required to break theseam. This is a bond strength level that would be expected with 500denier fiber, using typical fiber adhesive under the best conditions.

(2) With a higher bond strength of 7 to 8 lbs., there is no advantagefor the loops over straight fiber because breaking force is the same inboth cases. This is a level of bond strength that would be expected witha 1000 denier fiber under optimum conditions.

(3) Therefore, the advantages of the loop construction occurs: (a) whenusing narrower fiber widths and/or fiber reinforcing materials such asmonofilaments and multi-filaments, wherein the area for adhesive bondbetween the film and the fibers is substantially reduced from thatobtainable with 1000 denier polypropylene fiber, and (b) as insurance orback-up protection for TD fibers of any denier, to protect againstlocalized non-deposition or unanticipated failure of the fiber adhesive.

EXAMPLE 7

Samples of a 3-ply paper bag, a 6 mil bag made of low-densitypolyethylene (LDPE), a 9 mil LDPE bag and a woven 1000 denierpolypropylene (PP) bag are cut to obtain samples of their sheetmaterials which are subjected to the following six sheetcharacterization tests:

Yield (ASTM D882) (expressed in lbs/inch of sample width) is ameasurement of the force the material can take without permanentdistortion and represents he static load carrying capability of theshipping sack material.

Dart drop (ASTM D1709). The lesser of the MD and TD values is used,measures in inch pounds the amount of energy required for a 11/2"diameter, 2 lb. ball to pass through a clamped film sample. This test isto evaluate the film's ability to absorb shock loads such as bag drop.

PPT (ASTM D2582) test measures the length of a tear caused by aone-pound sharp projection which moves into and parallel to a 8-inchwide film sample after a 20-inch free drop. The result is converted toan average force in pounds required to make that length of tear. It isused as a measure of snag resistance. The lesser of the MD and TD valuesis used.

Elmendorf initiated tear (ASTM D1922) measures the average force ingrams that it takes to propagate an initiated tear and is used tomeasure the film material's ability to prevent slight punctures frompropagating to a large opening. The lesser of the MD and TD values isused.

Puncture measures the force in pounds that it takes a 0.937" diameterhead to penetrate through a clamped film sample. It is used as a measureof resistance to a finger or blunt object puncture.

The 9 mil LDPE bag is a square-bottomed bag, made on a WindmillerHolsher machine, which is the standard bag in Europe.

The woven polypropylene bag is fabricated with sewn seams.

Then single samples of these commercial bags are also subjected to thefollowing four performance tests:

The progressive end drop is used to evaluate the bag material, as thistest orientation results in the most severe loads on a given material ata given drop height. The procedure is to start at 2 ft. and continue todrop the same bag at progressively greater heights at one footincrements til the bag breaks.

The progressive edge drop is used to check the bottom and top seams ofthe bag. At a given drop height, this test orientation results in thegreatest loads on the end seams.

The 6-side drop is specified in the heavy duty plastic bag specificationadopted by some shipping associations. In this test, a bag is droppedfrom a specified height, once on each end, once on each edge, and onceon each face. Nine out of 10 bags should pass this test without failure.

The results of the six sheet characterization tests and the three bagperformance tests are given in the first four columns of Table II.

EXAMPLE 8

A fiber-reinforced composite sheet 200 of this invention, more simplytermed a fiber/film laminate having an overall thickness of 2.5 mil andan appearance as seen in FIGS. 18 and 19, is made from co-extruded filmof one mil thickness, which comprises 25% high-density polyethylene(HDPE) and 75% of low-density polyethylene (LDPE), and from 500 denierMD and TD fibers. The laminate is subjected to the same sixcharacterization tests.

Then the laminate is formed into a tube of indefinite length, having alap seam 210 as seen in FIGS. 20 and 21, which is cut into suitablelengths for making shipping sacks. The lengths are sewn at their ends.They are subjected to the same three performance tests as in Example 7.

The sheet characterization and bag performance test data are given inthe fifth column of Table II. The results indicate superiorcharacteristics and performance in most categories.

EXAMPLE 9

The same procedure is used in making a fiber/film laminate having a 2.75mil overall thickness, using the same co-extruded film but with 500denier MD fibers and 1000 denier TD fiber.

The same characterization and performance tests are performed as inExamples 7 and 8. The data are given in the sixth column of Table II. Itis apparent that the laminate has equivalent properties to the materialused for the 9 mil LDPE bag, although drop performance is not quite asgood.

                                      TABLE II                                    __________________________________________________________________________                COMMERCIAL BAGS      FIBER/FILM LAMINATES                         __________________________________________________________________________    Overall Film-Plus-                                                                        3 Ply                                                                              6 Mil                                                                              9 Mil                                                                              4 Mil 2.5 Mil                                                                            2.75 Mil                                                                           3.0 Mil                            Fiber Thickness                                                               Film Composition                                                                          (150 Lb                                                                            LDPE LDPE Woven PP                                                                            LD/HD                                                                              LD/HD                                                                              LD/HD                                          Paper)         (31/2 oz/                                                                     yd.sup.2)                                          Deniers of MD/TD                                                              Fibers      --   --   --   1000/750                                                                            500/500                                                                            500/1000                                                                           1000/1000.                         Fiber Material                                                                            --   --   --   PP    PP   PP   PP                                 __________________________________________________________________________    Example No. 7    7    7    7     8    9    10                                 __________________________________________________________________________    Material                                                                             ASTM                                                                   Tests: No.                                                                    Yield, lbs/in                                                                        D882 45   9    11   100   20   20   30                                 Dart Drop,                                                                           D1709                                                                              13   45   60   60    45   60   60                                 in-lbs*                                                                       PPT, lbs*                                                                            D2582                                                                              7.5  11   22   28    13   13   15                                 Tear, grams*                                                                         D1922                                                                              180  350  700  N/A   700  700  800                                Puncture, lbs                                                                        --   39   37   71   N/A   42   54   58                                 Bag Performance Tests:                                                        End Drop, Height in                                                                       2/35**                                                                             10/35**                                                                            10/55**                                                                            5/100***                                                                            5/50**                                                                             8/50**                                                                             5/100***                           ft/wt in lbs at                       5/100***                                Break                                                                         Edge Drop, Height in                                                                      --   --   --   6/100***                                                                            --   8/50**                                                                             6/100***                           ft/wt in lbs at                       4/100***                                Break                                                                         6 Side Drop, Height                                                                       --   --   10/55                                                                              4/100***                                                                            4/50**                                                                             8/50**                                                                             4/100***                           in ft/wt in lbs,                      4/100*                                  with No Damage                                                                __________________________________________________________________________     *Lower of MD or TD Values                                                     **LDPE Resin                                                                  ***Whole Corn                                                                 N/A Not Applicable                                                       

EXAMPLE 10

The same procedure is used in making a fiber/film laminate having anoverall thickness of 3.0 mil, using the same co-extruded film but with1000 denier MD and TD fibers.

The same sheet characterization and bag performance tests are performedas in Examples 7-9. The results are listed in the last column of TableII. It is evident that this fiber/film laminate has equivalentperformance to the woven PP bag. The sewn seam is the weak point of thewoven PP bag.

What is claimed is:
 1. In an apparatus for forming a single fiber into aplurality of transverse-direction reaches and into a plurality of loopsconnecting said reaches at each end thereof, said reaches and said loopsbeing straddled by a pair of films of indeterminate length forsubsequent lamination thereto to form a fiber-reinforced composite filmsheet and said apparatus comprising a pair of endless roller chainswhich are disposed to revolve in a pair of elongated patterns, each saidpattern comprising an interweaving section, a diverging section, and aparallel section, wherein each said chain comprises a row of linkedrollers and a row of spindles which are attached to but laterally offsetfrom said row of rollers to project outwardly from said pattern, whereineach of said spindles can rotate about its axis, an improved auxiliarydrive means for increasing the rotational speeds of said spindles beyondthe rotational speeds imparted by said fiber, said means comprising adrive surface which contacts said spindles at approximately 180° to saidreaches in at least said diverging section.
 2. The apparatus of claim 1,wherein said drive means further comprises a motor and a mounting meanstherefor, said motor being drivingly connected to said drive surface. 3.The auxiliary drive means of claim 2, wherein said drive motor is an airmotor and said drive surface is an elastomeric-surfaced roll.
 4. Theauxiliary drive means of claim 3, wherein at least four said drive meansare mounted within said diverging sections to enable said apparatus toattain a forward speed of at least 35 feet per minute.